The flash mob is to 21st century America what the torchlight parade was to 19th century America.

It draws attention, it celebrates, it’s loud and public and it’s fun.

The flash mob can be activist, too, and though it’s loud, it can be comforting.

On Sunday, May 19, the flash mob went activist and comforting at Buttonwood Park Zoo with about 40 people, organized by Kathy Tsonis, Oncology Outreach Coordinator for Southcoast Centers for Cancer Care. Tsonis works out of Southcoast’s Fairhaven site.

The mob descended and danced during the second annual Cancer Survivor Celebration when 178 survivors, supporters and family members gathered for a complementary lunch and a variety of activities. About 500 people attended the event.

“So we decided to do a flash mob,” Tsonis said.

To that end, she rounded up about around 20 Southcoast employees and another 20 of their family members. Along the way, she met Nathan Setera, a choreographer who had some experience with flash mobs.